RE: Estimate versus Compute

Mike, I don't believe that is true. I recently reduced from compute to estimate=25% and this reduced the runtime for update stats from 38 hours to 14 hours. I don't think it would make such a difference if it still had to visit every block. I think you can specify whether your samples are based on rows or blocks and Oracle will automatically compute if you specify estimate >= 50%.

Regards,
Brandon

-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Michael McMullen Sent: Monday, July 25, 2005 11:28 AM
To: mark.powell_at_eds.com; Oracle-L_at_freelists.org Cc: klange_at_ppoone.com
Subject: Re: Estimate versus Compute

. . .

I read somewhere, can't remember where, that when estimating one should use an estimate of 1 percent because anything else means all blocks get visited.

. . .

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